In the adhesive industry formulators typically blend either partially-hydrolyzed polyvinyl alcohol or fully-hydrolyzed polyvinyl alcohol with vinyl acetate/ethylene copolymer emulsions to obtain adhesive compositions having varying properties. When blended with a fully-hydrolyzed polyvinyl alcohol, a water resistant adhesive suitable for making cardboard packaging is obtained. When blended with a partially-hydrolyzed polyvinyl alcohol, the water sensitive adhesive product is suitable as the moistenable adhesive on envelop flaps. Prior to the present invention there was no single vinyl acetate/ethylene emulsion product which was compatible with both partially-hydrolyzed and fully-hydrolyzed polyvinyl alcohols and also afforded an emulsion-polyvinyl alcohol blend having enhanced plasticizer thickening.
U.S. Pat. No. 3,827,996 discloses aqueous dispersions of vinyl ester polymers prepared in the presence of a stabilizing amount of polyvinyl alcohol having an average residual vinyl acetate content of 5 to 7 mole%. A single polyvinyl alcohol having this vinyl acetate content may be used or a combination of polyvinyl alcohols having average vinyl acetate contents of up to about 16 mole% may be blended to produce an average of 5 to 7 mole%. The resulting vinyl ester polymer dispersions are said to possess stability, both during and after preparation, water resistance of the adhesive after it has been deposited from the dispersion and a satisfactory viscosity index.